B.C.'s Coroner Service said it was unable to confirm a cause of death for the Polish man who died at the Vancouver International Airport on Sunday after RCMP used a stun gun to subdue him.

The deceased was identified as Robert Dziekanski, 40, of Pieszyce, Poland.

There was no trauma, disease or any other obvious cause of death for Dziekanski, said assistant-deputy chief coroner Jeff Dolan.

Toxicology or microscopic examination may determine why he died, Dolan said.

An Integrated Homicide Investigation Team release says Dziekanski arrived from Poland on Saturday afternoon and was planning to live with his family in B.C.

RCMP Sergeant Pierre Lemaitre says police were called by airport security when the man began throwing chairs, pounding glass walls and acting irrational, despite orders to calm down.

A witness who used her cellphone camera to film Dziekanski being subdued and Tasered described him as shaking, sweating and "shouting back" at police. Sima Ashrafinia said that Dziekanski smelled of alcohol.

Dziekanski had been travelling and waiting at airports for at least 24 hours: Early Saturday, he took a five-hour bus ride from Poland to Frankfurt. He would have arrived two hours ahead of his plane from Frankfurt to Vancouver, which is typically an 11-hour flight. But it was late arriving to Vancouver, adding another two hours to the trip.

The flight finally arrived at the Vancouver International Airport at about 3:30 on Saturday afternoon.

As a new immigrant, it took a long time to process Dziekanski.

His mother gave up waiting and returned home to Kamloops at 10 p.m. on Saturday night.

Canada Border Services won't say how long he was in Customs and Immigrations and it's unknown how long he may have been wandering around the airport, trying to find his way out to the public meeting area.

But he was still at the airport well after midnight.

"I just heard shouting 'Politzia," Ashrafinia told CTV British Columbia.

"He was asking for police, he was shouting out of frustration," she added.

Canada Border Services offers translation services but there are fewer airport personnel around after midnight and little multilingual signage.

RCMP arrived shortly after 1:30 a.m. and Dziekanski was dead within minutes.

The RCMP has said it does not believe the man's death was related to the Taser, and that the man was shocked twice.

The incident is being investigated by the RCMP's civilian oversight body.

With a report from CTV British Columbia's Peter Grainger in Vancouver